Stack elevator and control theeefok



G. w. VON HOFE ET AL 2,733,920

STACK ELEVATOR AND CONTROL THEREFOR Feb. 7, 1956 2 Sheets-Sheet l Filed Aug. 15, 1951 INVENTORS GEORGE 1M mum 0n: y 50M A. WOLFF HTTORNEVE Feb. 7, 1956 G. w. VON HOFE ET AL 2,733,920

- STACK ELEVATOR AND CONTROL THEREFOR Filed Aug. 15, 1951 2 Sheets-Sheet 2 q INVENTORS Patented Feb. 7, 1956 STACK ELEVATOR AND CONTROL THEREFOR George W. von Hofe, Bound Brook, and Edwin K. Wolff, Palisades Park, N. J., assignors to New Jersey Machine Corporation, Hoboken, N. J., a corporation of New Jersey Application August 15, 1951, Serial No. 241,902

15 Claims. (Cl. 271 -31) This invention relates to machines of the type in which sheets of paper for use as box coverings, labels, box wraps and the like are applied to articles such as boxes, flat paper or other boards or the like. Machines of this type usually feed the sheets of paper from a stack in successive fashion to mechanism for performing some operation thereon, as for example, applying a coating of adhesive thereto, and then convey the thus processed sheets to the articles for application thereto. In existing machines of the indicated type it is difiicult and not always possible to replenish the stack of sheets without shutting down the machine with the necessity for bringing the machine again into proper operation and the consequent loss of production and increased cost.

It is the primary purpose of the present invention to provide an improved means whereby the stack of sheets may be readily replenished without interruption in the operation of the machine.

Other objects and advantages of the invention, as well as the novel features of construction thereof, will appear from a perusal of the following description when read in connection with the accompanying drawings in which Fig. l is a fragmentary sectional elevation of a machine embodying the invention; Fig. 2 is a side elevational view, on an enlarged scale, of the stack elevating mechanism shown in Fig. l, the view being taken from the right of Fig. 1; Fig. 3 is an enlarged detailed elevational view of the vacuum control means for the main stack elevating mechanism; Fig. 4 is a side elevational view, partly in section, of the upper stack supporting means, and Figs. 5 and 6 are detailed side elevational views showing the manner in which the feeler member for the elevating mechanism operates.

For the purposes of illustration and explanation, the invention is shown in the drawings as incorporated in a well known form of machine for applying sheets of paper to hollow containers, it being understood that the invention is not in any sense limited to such application, but may be used to equal advantage in other machines for other purposes.

In a machine of the type illustratetd there is provided a runway 10 leading to the point at which application of the sheets, labels or the like, takes place. Suitable means are associated with the runway 10 for properly advancing the articles, such as hollow containers 11 to such point of application. The sheets which are to be adhered to the containers 11 are fed in successive fashion from the top of a stack 12 of such sheets. The means for transferring the sheets in individual succession from the stack 12 comprises a suction head 13 pivotally connected at 14 with a member vertically movable in any well known way relatively to the stack 12 to pick up the uppermost sheet thereof. Mechanism of any conventional type is provided for swinging the suction head 13 on the pivot 14 in a manner to transfer or deliver the sheet carried by such head to a pair of feeding rollers 15 and 16. Suction is developed in the suction head 13 through a tube 17 which is attached at its other end to a suitable valve connected to a source of suction, as for instance, a suction pump. Suction is provided to the head 13 by the valve in predetermined relationship to the cycle of movements of such head by any suitable means. Preferably such means is so constructed and designed that suction is provided in the suction head 13 just prior to the time it engages the topmost sheet in the stack 12 and during the transfer of the leading edge of such sheet to the feeding rollers 15 and 16.

The feed roller 15 is journalled in the machine for rotational movement about a ,fixed axis and is intermittently driven in any suitable manner. The cooperating roller 16 is an idler roller carried by a shaft 18 which is carried by suitable means constructed and arranged to periodically move such shaft toward and away from roller 15, the arrangement being such that during the transfer of a sheet by the suction head 13 the roller 16 is spaced from the roller 15, as shown in Fig. l of the drawings, so that the suction head can insert the leading edge of such sheet between rolls 15 and 16 which are stationary at that time. As soon as the leading edge of the sheet has been properly inserted between the spaced rollers 15 and 16, the latter is shifted towards the roller 15 so that the leading edge of the sheet becomes gripped between both rollers. At this stage, roller 15 is given its periodic rotation to cause the sheet to be fed into engagement with the surface of an adhesive applying roll 19 which is adjacent to a transfer roll 20 journalled to rotate in a supply of suitable adhesive material provided in a container 21. The space between rollers 19 and 20 may be adjusted in any suitable manner to deliver the proper thickness of the adhesive to roller 19. The sheet engaging the adhesive coated surface of roller 19 is carried along thereby until it reaches a suitable pick-off device 22 which detaches such sheet from roll 19 and deflects the same into engagement with the surface of a deflecting roll 23. The latter roll continues the travel of the sheet and brings its advancing or leading edge into surface engagement with the advancing end of the container 11 which projects at this time slightly beyond the delivery end of the runway 10. At the proper time a device 24 in the form of a segmented cylinder and carried by shaft 25, is rotated by the latter so as to cause such device 24 to cooperate with roll 23 to apply a rolling pressure to the bottom of the container 11 and the sheet and thereby securely adhere the two together. During this application of the sheet to the container they are moved onto a conveyor 26 which advances them to a place of discharge or to additional means for further manipulation of the sheet. At this time also, the roller 16 will have moved away from the feed roller 15 so that the sheet will be drawn from the rollers 19 and 23 by the container 11 which is'being shifted over the roller 23 by the device 24. After the attachment of a sheet toa container 11 the above described cycle of operations will be'repeated using a new sheet and a new container 11.

While the machine is operating in the manner above described, mechanism automatically maintains the top of the stack 12 at a proper level for cooperation with the suction head 13. As is shown more clearly in Fig. l of the drawings, the stack 12 is supported by a main table 30 provided with racks 31, 31 which mesh with pinions 32 carried by a shaft 33 suitably journalled on the frame of the machine. The shaft 33 is periodically rotated by means of a ratchet wheel 34 keyed to such shaft and a cooperating pawl 35 to turn pinions 32 so as to raise the racks 31 and thereby to elevate the table 30. The pawl 35 is carried. on one arm of an actuating lever 36 pivotally mounted on shaft 33 and provided on another arm with a roller 37 which is in rolling engagement with a cam 38, such engagement of roller 37 which cam 38 rotatably mounted on shaft 41. The arm of lever 42 is pivotally connected to the upper end of a vertically disposed link 43 which is connected at its lower end to a follower arm 44 mounted for pivotal movement on a fixed shaft 45. The arm 44 is provided with a roller 46 which is in rolling engagement with a cam 47 and is -maintained in such relationship by means of a spring 48. It will thus be seen that cam 47 will periodically actuate follower arm 44, link 43 and lever 42 to pivotally move the mouth of the member 40 into and out of engagement with the top of the stack 12. The pivotal movement of member 40 is such that in its retracted position it will be substantially vertical and located to One side of the stack 12 so as not to interfere with the withdrawal of the topmost sheet from the stack by the suction device 13. The member 40 is provided with a passageway 40' which is periodically connected to a source of suction when such member is in an advanced or down position. The means for providing suction in passageway 40' includes a tube 50 attached at one end to such passageway, and at its other end to a valve 51, which is controlled by a lever 52 and a cam 53. The lever 52 is provided at one end with a cam roller 54 which is maintained in rolling engagement with the cam 53 by means of a spring 55. The other end of lever 52 is provided with a valve element 56 which seats on a port 57 of valve 51 when the parts are in the positions shown in Fig. 1 of the drawings. Port 57 is connected by a passageway 51' in valve 51 and by a tube 58 to a source of suction, such as a suction pump. Port 57 is also connected by a passageway 51" in valve 51 with tube 50 and by a passageway 51" with a tube 59 which is connected to a suction chamber 61 provided on the pawl supporting arm oflever 36 and having one wall thereof formed by a diaphragm 60 (note Fig. 3 of the drawings). The chamber 61 and diaphragm 60 form part of a control unit (generally designated 67) for the pawl 35, such unit 67 also including a rod 62 connected at one end to diaphragm 60 and connected at its other end to one end of a spring 63 carried by a bracket member 64 mounted on the end of lever 36 in which is formed the suction chamber 61. The rod 62 is provided with an adjustable nut 65 which engages with an arm '66 formed on pawl 35 to limit the advanced position of such pawl and to retract or raise the pawl 35 when the diaphragm 6!) and consequently rod 62 is pulled back by suction in chamber 61. The pawl 35 is substantially heavier than its arm 66 so that it normally tends to move toward the ratchet wheel 34 by gravity when permitted by the nut '65.

It will be understood from the foregoing, that the cam 53 is designed to unseat valve member 56 while the in dexing member 40 is being withdrawn from the stack 12, thus causing the suction applied at valve 51 to become inoperative past such valve by leakage of the atmosphere through port 57. Therefore during this period there will be no vacuum applied at member 40 and the vacuum chamber 61 on lever 36. Under such conditions the diaphragm 60 and consequently rod 62 and spring 63 will be in their normal positions with nut 65 permitting the pawl 35 to engage and advance ratchet wheel 34 on the next rocking movement of lever 36 about shaft 33. When the member 40 is next advanced toward the stack 12, cam 53 will cause valve member 56 to seat on port 57, thus stopping leakage of the atmosphere therethrough and connecting the passageway 40' in member 40 and the suction chamber 61 on lever 36 to the source of suction.

If the stack 12 is not high enough to close completely the open end of passageway 40', the vacuum .pressure in such passageway will be dissipated and a sufficient condition of suction in the suction chamber 61 to operate diaphragm 60 will be prevented. The relation of the parts connected with diaphragm 60 will therefore not be disturbed and pawl 35 will advance ratchet wheel 34 to elevate the table 30 on the next rocking movement of lever 36. However, if stack 12 is high enough when the indexing member comes down to completely close the open end of passageway 40', there will be created a sufficient condition of vacuumin chamber 61 to cause diaphragm 60 to be pulled back against the tension of spring 63. With the retraction of diaphragm 60, nut will force arm 66 to rotate pawl 35 in a clockwise direction, as viewed in Fig. 3 of the drawings. This raises pawl 35 from ratchet wheel 34 and prevents the coaction of such parts to raise the table 30 on the next rocking movement of lever 36 about shaft 33.

The stack 12 is normally supported on a removable auxiliary table mounted on the main table 30. When the main table 30 is raised by the mechanism previously described, to the extent that the auxiliary table 70 is moved past inwardly projecting ends of a plurality of hinges 71., such hinge ends are lifted by the auxiliary table, as shown in dotted outline in Fig. 4 of the drawings. A pair of such hinges 71 are mounted in spaced relation on each of two horizontally disposed arms 72 provided on the upper end of a pair of vertically disposed supports 73 (compare Figs. 1, 2 and 4) and extending along the sides of the stack 12. The sides of auxiliary table 70 project outwardly from the sides of the main table 30 and as soon as the auxiliary table 70 has sufficiently raised the hinges 71 the latter will pivot back to their normal at-rest positions on arms 72 (note Fig. 4) with the inwardly projecting ends thereof beneath the projecting side edges of table 70. Mounted on the arms '72 adjacent to each hinge 71 is a vertically disposed guide member 74 having outwardly curved top and bottom ends. Supports 73 are mounted on the upper ends of a pair of vertically disposed racks 75 with which are engaged pinions 76 secured to a shaft 77. Connected to shaft 77 is a sprocket 78 carrying one end of a chain 79 which is carried at its other end by a sprocket 80 mounted on a shafts]. Keyed to shaft 81 is a ratchet wheel 82 which is advanced by an auxiliary pawl 83 rotatably mounted on the outer end of a lever 84 secured to a hollow shaft 85 which is suitably mounted for rotary movement and through which shaft 81 extends. The pawl 33 is similar in construction to the previously described pawl 35. Also keyed to shaft 85 is a lever 86 which is connected by a link 87 to a lower arm 88 of lever 36. It will thus be seen that the rocking movements of lever 36 are transmitted through arm 88 of such lever, link 87, lever 86, shaft 85 and lever 84 to the pawl 83. The engagement of pawl 83 with ratchet wheel 82 is automatically controlled by an auxiliary unit 67 (note Fig. 2), which is substantially similar in construction to the previously described control unit 67 for pawl 35 and connected to valve 51 by the tube 59' (note Fig. '1). Thus the control unit 67' will be operated in the same manner as and simultaneously with the control unit 67 to control the operations of pawl 83 during the oscillating movements of the indexing member 40.

The engagement of pawl 35 with its associated ratchet wheel 34, and of pawl 83'with its associated ratchet wheel 82 are also controlled by manually operated hand levers 92 and89, respectively. In the'operation of the machine, one of such hand levers is always thrown to render its associated pawl inoperative. Thus in the normal operation of the machine, hand lever 89 is thrown torender pawl 83 inoperative while when the stack is to be replenished in the manner hereinafter explained, hand lever 89 is :moved to enable pawl 83 to be automatically controlled by the indexing member 40 and hand lever 92 is thrown to render pawl 35 inoperative. Asis shown in Figs. 1 to 3 of the drawings, hand lever 92 is keyed to a rotatabl shaft 93 and is provided with a pin 94 which when lever 92 is manually moved in a clockwise direction from the position shown in Fig. 3 of the drawings, engages the free end of the arm 66 of pawl 35 and disconnects such arm from the nut 65 on threaded rod 62. The pawl 35 is thereby maintained in a raised position unable to partake of the movements of diaphragm 60, rod 62 and nut 65, and unable to coactively operate with the ratchet wheel 34 to raise the table 30. When lever 92 is so pivoted to raise pawl 35, a pawl 35' secured to shaft 93 (note Figs. 1 and 2) is moved out of engagement with ratchet wheel 34 to permit rotation in either direction of shaft 33. When it is desired that pawl 35 resume its operations, lever 92 is thrown to the left, to the position shown in Fig. 3 of the drawings, whereupon pawl 35 will pivot under its own weight to bring the arm 66 thereof into coactive engagement with the nut 65 on rod 62. Pawl 35' follows each movement of the lever 92. For the sake of convenience, a

.second hand lever 92 is provided on shaft 93 at the other side of the machine. In a similar manner, the hand lever 89 is connected to a shaft 90 and provided with a pin 91 (note Fig. 2), which engages with the arm of pawl 83 to rotate such pawl to an inoperative raised position. Like lever 92, lever 89 is provided with a holding pawl 83' for engagement with ratchet wheel 82.. A second hand lever 89' is also secured to shaft 90 on the other side of the machine for the sake of convenience.

When hand lever 92 is thrown to render its associated pawls 35, 35' inoperative so that shaft 33 can be rotated the main table 3th may be raised or lowered by means of a pair of hand cranks detachably mounted on the ends of shaft 33. In a similar fashion, hand cranks are provided on the ends of shaft 81 to raise or lower racks 75 and consequently supports 72 when hand lever 89 is thrown to render its associated pawls 83, 83' inoperative. Each crank has a pin through its hub adapted to interengage with a slot formed on its associated shaft end to detachably connect such crank to the shaft. In Fig. 2 of the drawings, the left hand crank 95 on shaft 81 is shown, while the right hand end and crank of such shaft has been removed to show the right hand end of shaft 33 which is directly in back of shaft 81, as viewed in Fig. 2 of the drawings. The crank 97 provided on the right hand end of shaft 33 is also shown in this figure as well as a slot 96 by which the cranks are mounted on their respective shafts.

From the foregoing, it will be understood that in the operation of the machine, the indexing member 40 acts as a feeler adapted during each downward movement in the oscillation thereof to test the position of the upper end of the stack of labels 12. As the height of the stack decreases because of the progressive removal of labels therefrom, the feeler 40 at the end of its downward stroke, is unable to create a condition of vacuum in the control units 57, 67 sufiicient to pull back the diaphragms 60 of such units, thereby enabling the pawls 35 and 83 to advance their associate ratchet wheels 34 and 82, respectively, if they are not otherwise prevented from doing so by the hand levers 92 and 39, respectively. In the normal operation of the machine, the lever 89 is thrown to render pawl 83 inoperative, so that under such a condition of the stack 12, pawl 35 will advance ratchet wheel 34 to raise rack 31 and consequently the main table 30 and the auxiliary table 79 by which the stack is directly supported, as lever 33 is rocked in the manner previously explained. During the operation of the machine, the stack 12 will become depleted to the extent that the auxiliary supporting plate 7 i will move past the hinges 71 and in so doing, will initially raise the inwardly projecting ends of such hinges and then allow the latter to drop back so that the hinges 71 will return to their normal at-rest positions on the upper edges of the arms 72 and the inwardly projecting ends thereof will be beneath the projecting side edges of the auxiliary plate 70. When the auxiliary plate is so positioned above the hinges 71 this will be an indication to the operator that the stack should be replenished. This may be accomplished by first turning one of the crank levers 95 on shaft 81 in a direction to raise racks and thereby supports 72 to bring the inwardly project ing ends of hinges 71 into engagement with the undersides of the edges of the auxiliary table 70. The guide members 74 cause the auxiliary table 70 to be properly seated on the hinges 71 if such table has become misaligned during the operation of the machine. The lever 89 is then thrown to the left, as viewed in Fig. 1 of the drawings, so that pawl 83 will operate ratchet wheel 82, shaft 81, sprockets 80, chain 79 and sprocket 78 to raise racks 75, supports 72 and auxiliary table 70 as lever 33 is rocking and under the control of unit 67 and indexing member 40 in the manner previously explained. The machine will then continue its normal operation with the auxiliary pawl 83 raising the stack 12 as the latter is depleted. Lever 92 is then thrown to the right, as viewed in Fig. 1 of the drawings, to remove the pawls 35, 35 from their operative association with ratchet wheel 34 and thereby to enable table 30 to be lowered. This is accomplished by turning one of the cranks 97 on shaft 33 in a direction to lower the racks 31. When table 30 has been sufiiciently lowered a second auxiliary table 70' is positioned thereon and a new supply 12 of sheets mounted on table 70' as shown in Fig. 1 of the drawings. By turning one of the cranks 97 in the opposite direction, the racks 31, table 30 and auxiliary table 70' are raised until the topmost sheet in the new stack 12' comes into engagement with the underside of auxiliary table 70 and the latter together with the original stack 12 is supported by the new stack 12', auxiliary table 70 and main table 30, as shown in Fig. l of the drawings. The lever 92 is then thrown to the left as viewed in Fig. 1 of the drawings and lever 89 thrown to the right as viewed in such figure so that as the machine continues its operation the pawl 35 will cooperate with ratchet 34 to raise all of the elements on table 30 as the stack 12 is being depleted. Stack 12 can then be readily consolidated with stack 12' by simply drawing out the auxiliary table 70 by a quick endwise movement in a direction parallel to the supports 72. The slight drop in stack 12 as it is consolidated with stack 12' can be taken care of either by turning one of the cranks 97 to slightly raise table 30 or by permitting the indexing member 40 and control unit 67 to operate on each downward movement of such member 40 to cause pawl 35 to raise the table 30 until the consolidated stack is at the height for proper cooperation with the suction device 13. The hinges 71 and supports 72 can then be lowered to the new position at which it is desired to have the auxiliary table 70' move past such hinges, by turning one of the cranks 95 in a direction to cause the lowering of racks 75. It will be noted that during this entire replenishing operation, the new stack 12' of sheets has been added and consolidated with the initial stack 12 without any interruption in the operation of the machine and without any interference with the feeding of the sheets from the top of the stack by the suction device 13.

The manner in which the indexing member 40 controls the operation of the elevating mechanisms is shown more clearly in Figs. 5 and 6 of the drawings. In both of these figures the stack 12 is shown with the edges of the sheets therein to be gripped and advanced by the suction head 13 engaging the guide member 29 associated with the main stack supporting table 30. Fig. 6 of the drawings shows the stack at a proper working height so that when the indexing member 40 comes down, the open end of passageway 49' therein will be closed thereby creating a condition of vacuum in the chambers 61 of the controls 67, 67' sufiicient to cause such controls to raise their associated pawls 35 and 83, respectively, and thus prevent the operation of the elevating mechanisms. It willbe noted from Fig. 6, that this is not accomplished by the indexing member exerting a pressure on the top of the stack,

as is the usualpractice, but by the slight raising of a .portion of theadvancin'g end of the topmost sheet in the stack, due to the lifting pressure ofthe atmosphere. exerted on the underside of the topmost sheet, as indicated by the arrows. This slight raising of a forward portion of the topmost sheet also causes the underlying portion of the second sheet to be slightly raised, as shown, so that during the operation of the indexing member 40 there is established a condition of loose flu'fi'iness in the forward or advancing edge portions of "the upper-sheets in -the stack. This condition of flufiiness en'ables'the suction device 13 to more easily pick up the topmost sheet because the frictional adhesiveness of such sheet for the next underlying sheet, at least in 'the .forward endthere'o'f, has'been destroyed. As the stack decreases in height, the movement of air, when the member 40next moves to its lowered position, as shown in Fig. 5, is still sufficient to slightly raise the forward edge portion of the uppermost sheet, but the distance between the mouth of the passage 40 and such sheet has increased to the extent that the air at atmospheric pressure is unable to cause the sheet to close such mouth of the passage 40' and passes instead over the sheet and into the passage 40' as is indicated by the arrows in Fig. 5 of the drawings. Under such condition, the controls 67, 67 will not raise their associated pawls 35 and 83, respectively, and the elevating mechanisms will be enabled to operate in the manner previously explained. It will thus be noted that whether the top of the stack is at a position to be elevated or not, the member 40 at the end of each downward movement, will not press the stack to consolidate it, but willfiufi? or raise the topmost sheets to determine the position of the top of the stack and as a consequence thereof will facilitate the operation of the-suction device 13. A further advantage of this construction is that the upward feed of the stack by the elevating mechanisms can never cause the top of the stack to become jammed against the member 40 in its lowered position because such member 40 utilizes only the top loose sheet to determine the position of the top of the stack.

While there has herein been described and illustrated in the drawings, a preferred embodiment of the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. The combination of a support for a stack of sheets, means for removing one sheet at a time from the top of the stack, means for elevating said support to maintain the top of the stack at a predetermined level, means including a movable suction device for periodically determining the level of the top of the stack, means including a second suction device controlled by the suction in the first mentioned suction device of said determining means to control the operation of said elevating means, and means'located between said suction devices for periodically and simultaneously connecting the suction devices of said determining means and said control means to a source of suction.

2. The combination of a support for a stack of sheets, means for removing one sheet at a time from the top of the stack, means including an actuating member for elevating said support to maintain the top of the stack at a predetermined level, means including a device having an air passageway opening at its feeler end for periodically determining the level of the top of the stack, means for controlling the operation of said elevating means including an air chamber having a diaphragm forming one wall thereof and means operatively connecting said diaphragm to said actuating member, and means located between said determining means device and said controlling means for periodically and simultaneously connecting the air passageway of said determining means device and the air chamber o f'said control means to a source of air pressure,

the pressure of air in said determining means device coutrolling the pressure of air in such chamber to cause said diaphragm to control the operableness of said actuating member.

3. The combination of means for supporting a stack of sheets, means for removing one sheet at a time from the top of the stack, means for elevating said supporting means to maintain the top of the stack at a predetermined level, and means for periodically determining the top of 'the'stack, said l'a'st'mentioned means being so constructed and arranged that in its periodic testing operations it does not press against the stack and is operative to separate a portion of the topmost sheet in the stack from the underlying sheet and said removing means being constructed and arranged to grip the separated portion of the topmost sheet in its removal operations.

4. The combination of means for supporting a stack of sheets, means for removing one sheet at a time from the top of the stack, means for elevating said supporting means to maintain the top of the stack at a predetermined level, and means for periodically determining the top of the stack, said last mentioned means being so constructed and arranged that it does not press against the stack and causes a separation of a portion of the topmost sheet in the stack from the underlying sheets during its testing operations.

5. The combination of means for supporting a stack of sheets, means for removing one sheet at a time from the top of the stack, means for elevating said supporting means to maintain the top of the stack at a predetermined level, and means for periodically determining the top of the stack, said last mentioned means being constructed and arranged to detect the presence of a top single sheet in the stack without pressing down upon the stack and by causing an air force to be applied to the under-surface of a portion of such top sheet.

6. In sheet feeding mechanism, a support for a stack of sheets, a vacuum device, means for periodically moving said vacuum device to a position adjacent to but not in pressing relation upon the top of the stack to detect the presence of a topmost sheet in the stack in feeding position, the suction in said device being controlled by the relation of such device with the topmost sheet in the stack, means controlled by the degree of suction in said vacuum device for raising the stack to position a sheet in feeding position in the absence of a sheet in such feeding position, a second vacuum device for removing a sheet positioned in said feeding position, and means for periodically moving said second vacuum device into a sheet removing position over the portion of the topmost sheet tested by said first mentioned vacuum device.

7. The combination of means for supporting a stack of sheets, means for removing one sheet at a time from the top of the stack, means for periodically sucking a portion of the uppermost sheet in the stack into a given position above the top of the stack, and means controlled by said sucking means for elevating the stack a controlled amount when the uppermost sheet in the stack is not sucked up to said given position by said sucking means.

8. The combination of means for supporting a stack of sheets, means for periodically testing the position of the topmost sheet in the stack and constructed and arranged to separate a portion of such topmost sheet from the stack when such sheet is in proper feeding position, means controlled by said testing means for raising the stack to position a sheet in feeding position in the absence of a sheet in such feeding position, and periodically movable means for engaging the portion of a topmost sheet separated from the stack by said testing means to remove such sheet from the stack.

9. The combination of means for supporting a stack of sheets, a vacuum device for periodically testing the position of the topmost sheet in the stack, means for periodically moving said vacuum device during its testing periods to a'p'ositio'n adjacent to but spaced from a portion of the topmost sheet of the stack, means for periodically applying to said vacuum device during its testing periods a suction sufficient to separate a portion of a topmost sheet from the stack when such sheet is in proper feeding position, periodically movable means for engaging the portion of a topmost sheet separated from the stack by said vacuum device to remove such sheet from the stack, and means controlled by the degree of suction in said vacuum device during its testing periods for raising the stack to position a topmost sheet in feeding position in the absence of a sheet in such feeding position.

10. The combination of means for supporting a stack of sheets, a vacuum device for periodically testing the position of the topmost sheet in the stack, means for periodically moving said vacuum device during its testing periods to a position adjacent to but spaced from a portion of the topmost sheet of the stack, means including a vacuum device for raising the stack to position a topmost sheet in feeding position in the absence of a sheet in such feeding position, means for periodically applying suction simultaneously to both of said vacuum devices during the testing periods of said first mentioned device, said vacuum devices being arranged to be in communication during the application of suction thereto and the suction in said first mentioned vacuum device controlling said second mentioned vacuum device to control said stack raising means, the suction created in said first mentioned vacuum device by said applying means during the testing periods of such device being sufiicient to cause the separation of a portion of a topmost sheet from the stack when such sheet is in proper feeding position, and a third vacuum device periodically movable into engagement with the portions of the topmost sheets separated from the stack by said first mentioned vacuum devices to remove such sheets from the stack.

11. The combination of means for supporting a stack of sheets, a vacuum device for periodically testing the position of the topmost sheet in the stack, means including a vacuum device for raising the stack to position a topmost sheet in feeding position in the absence of a sheet in such feeding position, means including a valve connecting both of said vacuum devices to a source of suction, said valve being constructed to simultaneously connect both of said vacuum devices to said source of suction and to each other, means for periodically actuating said valve to connect both of said vacuum devices to said source of suction and to each other during the testing periods of said first mentioned vacuum device, the degree of suction in said first mentioned vacuum device controlling said second mentioned vacuum device to control said stack raising means, and a third vacuum device periodically movable to remove the topmost sheets from the stack intermediate the testing periods of said first mentioned vacuum device.

12. The combination defined in claim 11 in which stack raising means includes a ratchet, a pawl and means for periodically advancing said pawl to advance said ratchet, and in which said second vacuum device includes a chamber periodically placed in communication with said first mentioned vacuum device by said valve and said valve actuating means, a diaphragm closing said chamber, and means connecting said diaphragm to said pawl and controlled by said diaphragm to control the operativeness of said pawl to advance said ratchet.

13. The combination of means for supporting a stack of sheets, a vacuum device for periodically testing the position of the topmost sheet in the stack and means for raising the stack to position a topmost sheet in feeding position in the absence of a sheet in such feeding position including a ratchet, a pawl, means for periodically advancing said pawl to advance said ratchet, a vacuum device including a suction chamber and a diaphragm closing said chamber, means for periodically connecting both of said suction devices to a source of suction and to each other during the testing periods of said first mentioned vacuum device, the degree of suction in said first mentioned vacuum device controlling the position of the diaphragm in said second vacuum device, means connecting said diaphragm to said pawl and controlled by said diaphragm to control the operativenes of said pawl to advance said ratchet, and means operable to disconnect the operable connection between said pawl and dia phragm and to render said periodic means unable to advance said ratchet through said pawl.

14. The combination of a vertically movable table, a member for supporting a stack of sheets removably mounted on said table, means supporting said table and movable vertically to raise and lower said table, transfer means normally located above said table and constructed and arranged to permit movement of said member with the stack thereon past such means as said member and stack is raised by said table and to prevent downward movement of such member and the stack past such means when the raised table is lowered to a position below such transfer means, second supporting means carrying said transfer means and movable vertically to raise and lower said transfer means, means for removing one sheet at a time from the top of the stack of sheets, elevating means including said first and second supporting means operable to raise said table and said transfer means in a step-bystep fashion, means for periodically determining the level of the top of the stack, means controlled by said determining means to control automatically the operableness of said elevating means to raise said table and transfermeans, selective means operable to enable said elevating, means to raise both said table and transfer means simultaneously and to render said elevating means inoperative: to raise both said table and transfer means at the same time, means operable when said elevating means has been rendered inoperative to raise said transfer means in a step-by-step fashion and after said table has raised said member and the stack carried thereby past said transfer means to a position above the latter, to raise said transfer means to transfer automatically said member and the stack carried thereby from said table to a starting position below said member and stack and above said table to said transfer means, and to lower said transfer means after said member and stack are again supported by said table, and without interfering with the step-bystep advancement of said table by said elevating means, and means operable when said elevating means has been rendered inoperable to raise said table in a step-by-step fashion, to lower said table to a starting position below said transfer means for the placement thereon of a second, removably mounted, stack supporting member supported by said transfer means and raises the same therefrom with a new stack of sheets, and to raise said table with the second member and new stack until the top of the latter engages with said first mentioned member so that said table supports both stacks and both members, and without interfering with the step-by-step advance ment of said transfer means by said elevating means.

15. The combination of a vertically movable table, a member for supporting a stack of sheets removably mounted on said table, rack means supporting said table and movable vertically to raise and lower said table, transfer means normally located above said table and constructed and arranged to permit movement of said member past such means as said member is raised by said table and to prevent downward movement of said member past such means, second rack means carrying said transfer means and movable vertically to raise and lower said transfer means, means for removing one sheet at a time from the top of the stack of sheets, elevating means including said first and second rack means, pinio-ns engageable with said rack means and pawls and ratchet wheels for driving said pinions, operable to raise said table and said transfer means in a step-by-step fashion, means for periodically determining the level of the top of the stack, means controlled by said determining means 11 to control automatically the operableness of said pawls and thereby the operableness of said elevating means to raise said table and transfer means, a pair of levers controlling said pawls and selectively operable to position said pawls to enable said elevating means to raise both said table and transfer means simultaneously and to render said elevating means inoperative to raise both said table and transfer means at the same time, means operable when said elevating means has been rendered inoperative to raise said transfer means in a step-by step fashion, to raise said transfer means to transfer automatically said member and the stack carried thereby from said table to said transfer means, and to lower said transfer means to a starting position after said member and stack are again supported by said table, and without interfering with the step-by-step advancement of said table by said elevating means, and means operable when said elevating means has been rendered inoperable to raise said table in a step-by-step fashion, to lower said table to a starting position for the placement thereon of a second stack supporting member with a new stack of sheets, and to raise said table with the second member 12 and new stack until the top of the latter engages with said first mentioned member so that said table supports both stacks and both members, and without interfering with the step-by-step advancement of said transfer means by said elevating means.

References Cited in the file of this patent UNITED STATES PATENTS 1,057,601 White Apr. 1, 1913 1,748,572 Johnson Feb. 25, 1930 1,764,018 Hallstream June 17, 1930 2,145,916 Belluche Feb. 7, 1939 2,204,985 Foweraker -a June 18, 1940 2,336,839 Blackstone Dec. 14, 1943 2,440,458 Bernard Apr. 27, 1948 2,530,670 Von Hofe Nov. 21, 1950 2,654,603 Williams Oct. 6, 1953 FOREIGN PATENTS 605,424 Great Britain July 22, 1948 

